Is managing horses ‘as wild’ beneficial for dung beetle assemblages and their associated ecological functions?

In Europe, where livestock has largely replaced wild ungulates over the centuries, dung beetle assemblages have become largely dependent on livestock farming. The radical changes in livestock farming practices during the 20th century have therefore had a profound impact on these assemblages. Trophic rewilding with large herbivores is an important focus in European rewilding projects, and dung beetle assemblages appear to be good indicators of the success of rewilding. By comparing the composition of dung beetle assemblages and the rate of dung disappearance in three neighboring grassland habitats in southern France, maintained respectively by a population of Przewalski horses managed by natural selection and two herds managed for production purposes (a flock of sheep and a herd of endurance horses), our study shows a) significant differences in the composition of the dung of the three animals; b) a single pool of dung beetle species; c) but a different assemblage structure. While tunnelers dominated across all the sampled habitats, rollers were the second most abundant group in domestic farms, and were replaced by dwellers in the Przewalski horse rangelands. Differences in dung beetle assemblages and dung composition between the three grazers could both explain that sheep droppings were removed faster than horse dung. Understanding how herbivore types and management shape these assemblages helps refine decisions for conservation and/or rewilding. However, the place of ecological heritage and species co-occurences in these changes need to be examined, since in this region the history of dung beetles is closely linked to that of sheep pastoralism as for other types of semi-natural grasslands in Europe. • A common species pool of dung beetles is shared by dry grasslands grazed by domestic horses, ‘as wild’ horses and sheep. • Sheep droppings are more rapidly removed by dung beetles than horse dung; telecoprids are favored by the presence of domestic herds, regardless of species, while endocoprids are favored by the presence of ‘as wild’ horses. • The differences between herbivore dung – and dung beetle assemblages - could be linked to the herbivore physiology (digestion, feeding choices), morphology and herd management (sociality and habitat use). • These results can help determine possible conservation management approaches, whether through domestic herds or rewilding.